As an interactive demo system emerging in recent years, an interactive electronic whiteboard can save writing content on the electronic whiteboard very conveniently into a computer, do such works as editing, modifying, labeling screen content of the computer on the interactive electronic whiteboard, and control the computer. However, effective combination of display and writing of the ultra-large screen has not been realized with a prior interactive electronic whiteboard due to a limitation of human's writing height. In large screen display, if the entire display is used as a writing plane, a large-sized electronic writing board will be required that is high in cost and also inconvenient to operate. In other words, size of the plane of the writing board is also limited by such factors as cost, which makes the large-sized interactive whiteboard difficult to be well applied in large council chambers, report halls, large classrooms, etc. Therefore, advantages of the interactive electronic whiteboards cannot be efficiently presented in such places as large council chambers, report halls, and large classrooms.